scientists track them and discover a kind of feline frankenstein. >>> good evening. we begin with that wall of wind howling across the country tonight. millions of americans bracing for the impact, everything from stalled trains and planes to tornadoes. and here is the map. an area from the florida panhandle to new york, under a severe weather warning. abc's steve osunsami is outside atlanta tonight in adairsville, georgia, where one powerful tornado has already torn through town. >> reporter: an hour north of atlanta, an amazing picture, the sky was falling. >> we've got debris flying to the left and center of this system. the sirens have been going off here. the wind is kicking up, along with the rain. again, a funnel crossing the interstate here in adairsville. >> reporter: witnesses here say the tornado was on the ground, churning through homes, office buildings and factories for more than 20 minutes. scientists think it was an ef-2 or greater, with wind speeds more than 125 miles an hour. >> please take safe shelter for us right now. get in the center portion of